Speaker device

ABSTRACT

A speaker apparatus has a magnetic circuit portion, a diaphragm, a secondary coil, at least one primary coil, a cylindrical member, and a positioning portion. The magnetic circuit portion has a magnet, a yoke for which the magnet is provided, and a top plate for forming a magnetic gap together with the yoke. The primary coil is arranged in the magnetic gap of the magnetic circuit portion. The secondary coil is provided for the diaphragm so as to face the primary coil in the magnetic gap. One side of the cylindrical member locating in the magnetic gap is attached to the primary coil, and the cylindrical member supplies a current to the primary coil. The positioning portion is provided for a yoke and positions the other side of the cylindrical member.

TECHNICAL FIELD

The invention relates to a speaker apparatus and, more particularly, toa speaker apparatus having a primary coil and a secondary coil.

BACKGROUND ART

Hitherto, an electromagnetic induction speaker has been known. As such aspeaker, there are what is called an inner magnetic type electromagneticinduction speaker in which a magnet is arranged inside and what iscalled an outer magnetic type electromagnetic induction speaker in whicha magnet is arranged outside.

As shown in FIG. 1, an inner magnetic type electromagnetic inductionspeaker 100 has a yoke 110, a magnet 120, and a diaphragm 130.

The yoke 110 is constructed by integratedly forming: a disk-shapedbottom portion 111; a peripheral wall portion 112 projected upward froma peripheral edge of the bottom portion 111; and a ring-shaped annularplate 113 provided at the upper edge of the peripheral wall portion 112.The cylindrical magnet 120 is attached to the center portion of theupper surface of the bottom portion 111. The upper surface of theannular plate 113 of the yoke 110 is attached to a frame 140.

A disk-shaped center plate 150 is attached to the upper surface of themagnet 120. The center plate 150 is arranged in a center hole 113 a ofthe annular plate 113. A gap formed between the annular plate 113 andcenter plate 150 is a magnetic gap 160.

The diaphragm 130 is constructed by integratedly forming: an almostsemispherical dome portion 131 provided in the center portion; and anedge portion 132 having a small arc-shaped cross section and formed soas to be continuous with the outer periphery of the dome portion 131. Anouter edge portion of the edge portion 132 is attached to the uppersurface of the frame 140. An upper edge of a cylindrical bobbin 170 isfixed to the outer peripheral edge of the dome portion 131 by adhesionor the like.

A secondary coil 171 of one turn is wound around a portion near thelower edge of the bobbin 170 and fixed. The secondary coil 171 islocated in the magnetic gap 160 formed between the annular plate 113 andcenter plate 150.

A primary coil 180 on the outer peripheral side and a primary coil 190on the inner peripheral side are arranged in the magnetic gap 160 so asto face each other through the secondary coil 171. The outer peripheralside primary coil 180 is fixed to the inner peripheral surface of theannular plate 113 of the yoke 110. The inner peripheral side primarycoil 190 is fixed to the outer peripheral surface of the center plate150. The outer peripheral side primary coil 180 and inner peripheralside primary coil 190 are serially connected. One end of the outerperipheral side primary coil 180 is connected to a signal lead wire 180a. One end of the inner peripheral side primary coil 190 is connected toa signal lead wire 190 a.

When a current based on an audio signal which is supplied from an audiosignal reproducing unit (not shown) is supplied to the outer peripheralside primary coil 180 and inner peripheral side primary coil 190, aninduction current flows in the secondary coil 171 arranged in themagnetic gap 160. The diaphragm 130 is vibrated by a Lorentz force. Theaudible sound based on the audio signal corresponding to the currentsupplied to the primary coil 190 is generated.

As shown in FIG. 2, an outer magnetic type speaker 200 comprises a yoke210, a magnet 220, and a diaphragm 230.

The yoke 210 is constructed by integratedly forming: a disk-shapedbottom portion 211; and a center pole 212 projected upward from thecenter portion of the bottom portion 211. The cylindrical magnet 220 isattached to an outer edge portion of the upper surface of the bottomportion 211.

A ring-shaped annular plate 240 is attached to the upper surface of themagnet 220. The annular plate 240 is arranged in correspondence to theupper edge portion of the center pole 212. An upper surface of the outeredge portion of the annular plate 240 is attached to a frame 250. A gapformed between the annular plate 240 and center pole 212 is a magneticgap 260.

The diaphragm 230 comprises: a center portion 231 having an arc-shapedcross section and locating in the center portion; an inclined portion232 which is provided so as to be continuous with the outer periphery ofthe center portion 231 and deviated upward as it approaches the outwardposition; an edge portion 233 which is continuous with the outerperiphery of the inclined portion 232; and a fixing portion 234 which isprovided so as to be continuous with the outer periphery of the centerportion 231 and is projected in the direction opposite to the inclinedportion 232. An outer edge portion of the edge portion 233 is attachedto the upper surface of the outer edge portion of the frame 250. Anupper edge portion of a cylindrical bobbin 270 is fixed to an edgeportion of the fixing portion 234 by adhesion or the like.

A secondary coil 271 of one turn is wound around a portion near thelower edge of the bobbin 270 and fixed. The secondary coil 271 islocated in the magnetic gap 260 formed between the annular plate 240 andcenter pole 212.

A primary coil 280 on the outer peripheral side and a primary coil 290on the inner peripheral side are arranged in the magnetic gap 260 so asto face each other through the secondary coil 271. The outer peripheralside primary coil 280 is fixed to the inner peripheral surface of theannular plate 240. The inner peripheral side primary coil 290 is fixedto the upper edge portion of the outer peripheral surface of the centerpole 212. The outer peripheral side primary coil 280 and innerperipheral side primary coil 290 are serially connected. One end of theouter peripheral side primary coil 280 is connected to a signal leadwire 280 a. One end of the inner peripheral side primary coil 290 isconnected to a signal lead wire 290 a.

When a current based on an audio signal which is supplied from an audiosignal reproducing unit (not shown) is supplied to the outer peripheralside primary coil 280 and inner peripheral side primary coil 290 in amanner similar to the speaker 100 shown in FIG. 1 mentioned above, aninduction current flows in the secondary coil 271 arranged in themagnetic gap 260. The diaphragm 230 is vibrated by a Lorentz force. Theaudible sound based on the audio signal corresponding to the suppliedcurrent is generated.

When the primary coils 180, 190, 280, and 290 mentioned above are fixedto the annular plates 113 and 240 or the center plate 150 or center pole212, there are generally the following two methods.

(1) In a state where the primary coils 180, 190, 280, and 290 are woundand fixed to the outer peripheral surface of the cylindrical bobbin (notshown), they are internally fitted to the annular plates 113 and 240 orexternally fitted to the center plate 150 or center pole 212 and fixedby adhesion or the like.

(2) In a state where the primary coils 180, 190, 280, and 290 are woundwithout using any bobbin (they are formed as bobbinless coils), they areinternally fitted to the annular plates 113 and 240 or externally fittedto the center plate 150 or center pole 212 and fixed by adhesion or thelike.

Generally, the foregoing bobbins and the primary coils 180, 190, 280,and 290 which are internally fitted to the annular plates 113 and 240 orexternally fitted to the center plate 150 or center pole 212 are verythin and their mechanical strengths are weak. Therefore, when they areinternally fitted to the annular plates 113 and 240 or externally fittedto the center plate 150 or center pole 212, it is necessary to preventthe occurrence of damage or the like by constructing them in such amanner that the bobbins and the primary coils 180, 190, 280, and 290 arenot come into contact with the annular plates 113 and 240, center plate150, and center pole 212.

Therefore, even by any of the foregoing methods, in a state where theprimary coils 180 and 280 are previously wound, their outer diametersare set to be slightly smaller than inner diameters of the annularplates 113 and 240, and the adhesive agent is filled in the gaps betweenthe primary coils 180 and 280 and the annular plates 113 and 240 tothereby fix them. In a state where the primary coils 190 and 290 arepreviously wound, their inner diameters are set to be slightly largerthan outer diameter of the center plate 150 or center pole 212, and theadhesive agent is filled in the gap between the primary coils 190 and290 and the center plate 150 or center pole 212 to thereby fix them.

However, since all of the annular plates 113 and 240, center plate 150,and center pole 212 are thin, there is a problem that an area of eachperipheral surface is small and adhesive strengths between the primarycoils 180, 190, 280, and 290 and the annular plates 113 and 240 and thecenter plate 150 or center pole 212 are weak.

Generally, in the inner magnetic type electromagnetic induction speaker100 shown in FIG. 1, after the inner peripheral side primary coil 190 isfixed to the center plate 150, the center plate 150 is fixed to themagnet 120 attached to the yoke 110 in a state where it has beenpositioned. In the outer magnetic type electromagnetic induction speaker200 shown in FIG. 2, after the outer peripheral side primary coil 280 isfixed to the annular plate 240, the annular plate 240 is fixed to themagnet 220 attached to the yoke 210 in a state where it has beenpositioned.

When the operation to fix the annular plate 240 to the magnet 220 isperformed, in order to keep predetermined gap intervals of the magneticgaps 160 and 260, a gap gauge is inserted between the outer peripheralside primary coil 180 and inner peripheral side primary coil 190 orbetween the outer peripheral side primary coil 280 and inner peripheralside primary coil 290 and the gap interval is adjusted so as to beconstant, thereby positioning each member. If the gap gauge is come intocontact with the primary coil 180, 190, 280, or 290 at the time of thepositioning operation, since the adhesive strength is weak, there is afear that the primary coil 180, 190, 280, or 290 is dropped out from theannular plates 113 and 240, center plate 150, or center pole 212.

DISCLOSURE OF INVENTION

It is an object of a speaker apparatus of the invention to solve theforegoing problems, enable a primary coil to be easily positioned, andimprove an attaching strength of the primary coil.

According to Claim 1, there is provided a speaker apparatus comprising:

a magnetic circuit portion having a magnet, a yoke for which the magnetis provided, and a top plate for forming a magnetic gap together withthe yoke;

at least one primary coil arranged in the magnetic gap of the magneticcircuit portion;

a diaphragm;

a secondary coil provided for the diaphragm so as to face the primarycoil in the magnetic gap;

a cylindrical member in which one side locating in the magnetic gap isattached to the primary coil and which supplies a current to the primarycoil; and

a positioning portion, provided for the yoke, for positioning the otherside of the cylindrical member.

In the speaker apparatus according to Claim 1, there is no need to use agap gauge in order to obtain a predetermined gap interval of themagnetic gap, and an attaching area of the primary coil increases.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic vertical sectional view showing a conventionalinner magnetic type electromagnetic induction speaker;

FIG. 2 is a schematic vertical sectional view showing a conventionalouter magnetic type electromagnetic induction speaker;

FIG. 3 is a schematic vertical sectional view showing the firstembodiment in which a speaker apparatus of the invention is applied toan inner magnetic type electromagnetic induction speaker;

FIG. 4 is a schematic vertical sectional view showing an inner magnetictype electromagnetic induction speaker in which a primary coil isarranged only on one side of a secondary coil;

FIG. 5 is a schematic vertical sectional view showing an inner magnetictype electromagnetic induction speaker in which a first cylindricalmember is directly fixed to an annular plate;

FIG. 6 is a schematic vertical sectional view showing an inner magnetictype electromagnetic induction speaker in which a positioning portion isformed as grooves;

FIG. 7 is a schematic vertical sectional view showing the secondembodiment in which the speaker apparatus of the invention is applied toan outer magnetic type electromagnetic induction speaker;

FIG. 8 shows the third embodiment in which the speaker apparatus of theinvention is applied to a conducting type speaker apparatus in which aconductive ring is fixed to a diaphragm together with FIG. 9 and is aschematic vertical sectional view of the speaker apparatus;

FIG. 9 is an enlarged vertical sectional view of a main portion;

FIG. 10 is an enlarged vertical sectional view of a main portion of aspeaker apparatus in which a bobbin is fixed to a diaphragm; and

FIG. 11 is an enlarged vertical sectional view of a main portion of aspeaker apparatus in which a bobbin formed with a bending portion isfixed to a diaphragm.

BEST MODE FOR CARRYING OUT THE INVENTION

Each embodiment of a speaker apparatus of the invention will now bedescribed hereinbelow with reference to the drawings.

In the embodiments shown below, the invention is applied to anelectromagnetic induction speaker.

First, an inner magnetic type electromagnetic induction speaker 1 shownin FIG. 3 will now be described as a first embodiment.

The inner magnetic type electromagnetic induction speaker 1 comprises ayoke 2, a magnet 3, and a diaphragm 4.

The yoke 2 is constructed by integrating an almost disk-shaped bottomportion 5, a peripheral wall portion 6 upwardly projecting from aperipheral edge of the bottom portion 5, and a ring-shaped annular plate7 provided on an upper edge of the peripheral wall portion 6. Apositioning portion 8 is formed on an upper surface of a center portionof the bottom portion 5.

The positioning portion 8 is formed in a stairway shape from the bottomportion 5 of the yoke 2 when it is seen as a vertical sectional shape,and a first stairway portion 9 and a second stairway portion 10 areformed integratedly with the bottom portion 5. The first stairwayportion 9 is formed in a disk-shape, its outer peripheral portion 9 a isused as a first stairway surface, and its upper surface 9 b ispositioned slightly upward from the upper surface of the bottom portion5. The second stairway portion 10 is formed in a disk shape fairlysmaller than the first stairway portion 9 and provided coaxially withthe first stairway portion 9. An outer peripheral surface 10 a is formedas a second stairway surface and an upper surface 10 b is positionedslightly upward from the upper surface 9 b of the first stairway portion9.

The cylindrical magnet 3 is attached to the center portion of the uppersurface 10 b of the second stairway portion 10. For example, the magnet3 is arranged in a positioning concave portion (not shown) formed on theupper surface 10 b of the second stairway portion 10, so that the magnetis arranged coaxially with the second stairway portion 10.

As for the yoke 2, the upper surface of the annular plate 7 is attachedto a frame 11. The inner peripheral surface of the annular plate 7 islocated slightly on the outer side from the first stairway surface 9 aof the first stairway portion 9, while the center axis of thepositioning portion 8 is used as a reference.

A disk-shaped center plate 12 serving as a top plate is attached to theupper surface of the magnet 3. The center plate 12 is arranged in acenter hole 7 a of the annular plate 7. The peripheral surface of thecenter plate 12 is located at the same phase as that of the secondstairway surface 10 a of the second stairway portion 10, while thecenter axis of the positioning portion 8 is used as a reference. A gapformed between the annular plate 7 and center plate 12 becomes amagnetic gap 13. A magnetic circuit portion is constructed by the yoke2, magnet 3, annular plate 7, and center plate 12.

The whole diaphragm 4 is formed in a dome shape. The diaphragm 4 isconstructed by integratedly forming an almost semispherical dome portion4 a locating in the center portion and an edge portion 4 b having asmall almost arc-shaped cross section and provided so as to becontinuous with an outer periphery of the dome portion 4 a. The outeredge portion of the edge portion 4 b is attached to the upper surface ofthe frame 11. The upper edge portion of a cylindrical bobbin 14 is fixedto the outer peripheral edge of the inner surface of the dome portion 4a by adhesion or the like. The diaphragm 4 and bobbin 14 can be fixedlyadhered by a method, which will be explained hereinlater.

A secondary coil 15 of one turn is wound around the portion (near thelower edge) of the bobbin 14 and fixed. The secondary coil 15 ispositioned in the magnetic gap 13 formed between the annular plate 7 andcenter plate 12.

A primary coil 16 on the outer peripheral side and a primary coil 17 onthe inner peripheral side are arranged in the magnetic gap 13 so as toface each other through the secondary coil 15. The outer peripheral sideprimary coil 16 and inner peripheral side primary coil 17 are seriallyconnected. One end of the outer peripheral side primary coil 16 and oneend of the inner peripheral side primary coil 17 are connected to signallead wires 16 a and 17 a to which an audio signal from an audio signalreproducing unit (not shown) is supplied, respectively.

The outer peripheral side primary coil 16 is wound around the outerperiphery of the upper edge portion of a first cylindrical member 18having a thin cylindrical shape and fixed. The first cylindrical member18 is formed so that its inner diameter is equal to the outer diameterof the first stairway portion 9. The inner surface of the lower edgeportion of the first cylindrical member 18 is adhered to the firststairway surface 9 a of the first stairway portion 9 of the positioningportion 8. The outer peripheral surface of the outer peripheral sideprimary coil 16 fixed to the first cylindrical member 18 is adhered tothe inner peripheral surface of the annular plate 7.

The outer peripheral side primary coil 16 fixed to the first cylindricalmember 18 is fixed to the yoke 2, for example, by a method whereby thefirst cylindrical member 18 is inserted from the upper position into theyoke 2, the lower edge portion of the first cylindrical member 18 isadhered to the first stairway surface 9 a, and the outer peripheralsurface of the outer peripheral side primary coil 16 is adhered to theinner peripheral surface of the annular plate 7.

The inner peripheral side primary coil 17 is wound around the outerperiphery of the upper edge portion of a second cylindrical member 19having a thin cylindrical shape and fixed. The second cylindrical member19 is formed so that its inner diameter is equal to the outer diameterof the second stairway portion 10. An inner surface of a lower edgeportion of the second cylindrical member 19 is adhered to the secondstairway surface 10 a of the second stairway portion 10 of thepositioning portion 8. An inner peripheral surface of an upper edgeportion of the second cylindrical member 19 is adhered to the outerperipheral surface of the center plate 12.

The inner peripheral side primary coil 17 fixed to the secondcylindrical member 19 is fixed to the yoke 2, for example, by a methodwhereby the second cylindrical member 19 is preliminarily and externallyfitted to the center plate 12, the inner surface of the upper edgeportion of the second cylindrical member 19 is adhered to the centerplate 12, and in a state where the second cylindrical member 19 has beenfixed to the center plate 12, the second cylindrical member 19 isinserted into the yoke 2 from the upper position of the yoke 2 togetherwith the center plate 12, and the lower edge portion of the secondcylindrical member 19 is adhered to the second stairway surface 10 a. Byexternally fitting the second cylindrical member 19 to the secondstairway portion 10 of the positioning portion 8, the positioning of theinner peripheral side primary coil 17 to the yoke 2 is performed, sothat the positioning of the center plate 12 to the magnet 3 attached tothe yoke 2 is also simultaneously performed. The center plate 12 isfixed to the magnet 3 by using proper means such as adhesion, screwing,or the like.

As mentioned above, in the inner magnetic type electromagnetic inductionspeaker 1 shown in FIG. 3, the positioning portion 8 is formed on theyoke 2, and the first cylindrical member 18 to which the outerperipheral side primary coil 16 has been fixed and the secondcylindrical member 19 to which the inner peripheral side primary coil 17has been fixed are merely externally fitted to the first stairwayportion 9 and second stairway portion 10 of the positioning portion 8,respectively, so that the positioning of the outer peripheral sideprimary coil 16 and inner peripheral side primary coil 17 to the yoke 2can be performed.

Therefore, since the positioning of the outer peripheral side primarycoil 16 and inner peripheral side primary coil 17 to the yoke 2 can beextremely easily performed and there is no need to use the gap gauge,there is no fear of dropout (the conventional problem mentioned above)from the yoke 2 or the like due to the contact of the gap gauge with theouter peripheral side primary coil 16 or inner peripheral side primarycoil 17.

The first cylindrical member 18 is adhered to the first stairway surface9 a of the positioning portion 8, the outer peripheral side primary coil16 fixed to the first cylindrical member 18 is adhered to the annularplate 7, and the second cylindrical member 19 is adhered to the secondstairway surface 10 a of the positioning portion 8 and adhered to thecenter plate 12, so that the number of adhering portions increases.Consequently, an adhering area increases and an adhering strength of theouter peripheral side primary coil 16 and inner peripheral side primarycoil 17 is improved.

As for the positioning portion 8, it is sufficient to merely form thetwo stairway portions 9 and 10 to the bottom portion 5 of the yoke 2 andthe positioning portion 8 can be easily formed.

In the foregoing positioning portion 8, although the stairway portions 9and 10 are formed so that the center portion of the yoke 2 is located atthe highest position, the positioning portion can be also provided byforming a concave portion in such a manner that the bottom surface isdeformed downward step by step so that the center portion of the yoke 2is located at the lowest position.

According to the inner magnetic type electromagnetic induction speaker 1shown in FIG. 3, the primary coils are arranged so as to face each otherthrough the secondary coil. However, the invention can be also appliedto an inner magnetic type electromagnetic induction speaker 1A as shownin FIG. 4 in which the primary coil is arranged only on one side of asecondary coil.

As compared with the inner magnetic type electromagnetic inductionspeaker 1 shown in FIG. 3, the inner magnetic type electromagneticinduction speaker 1A shown below merely differs from the speaker 1 withrespect to a point that a primary coil is arranged only on one side of asecondary coil and only one stairway portion is provided as apositioning portion in correspondence thereto. In an explanation of theinner magnetic type electromagnetic induction speaker 1A, only differentportions from those of the inner magnetic type electromagnetic inductionspeaker 1 will be described in detail. The other portions are designatedby the same reference numerals as those shown in the similar portions inthe inner magnetic type electromagnetic induction speaker 1 and theirdescriptions are omitted.

As for a positioning portion 8A, a disk-shaped stairway portion 10A isformed and its outer peripheral surface 10 c becomes a stairway surface.

A primary coil 17A is arranged in the magnetic gap 13 at a positionbetween the secondary coil 15 and center plate 12. The primary coil 17Ais connected to the signal lead wire 17 a to which an audio signal froman audio signal reproducing unit (not shown) is supplied.

The primary coil 17A is wound around an outer periphery of an upper edgeportion of a cylindrical member 19A having a thin cylindrical shape andfixed. The cylindrical member 19A is formed so that its inner diameteris equal to an outer diameter of the stairway portion 10A. An innersurface of a lower edge portion of the cylindrical member 19A is adheredto the stairway surface 10 c of the stairway portion 10A of thepositioning portion 8A. An inner peripheral surface of an upper edgeportion of the cylindrical member 19A is adhered to the outer peripheralsurface of the center plate 12.

The primary coil 17A fixed to the cylindrical member 19A is fixed to theyoke 2, for example, by a method whereby the cylindrical member 19A ispreliminarily and externally fitted to the center plate 12, an innersurface of an upper edge portion of the cylindrical member 19A isadhered to the center plate 12, and in a state where the cylindricalmember is fixed to the center plate 12, the cylindrical member 19A isinserted into the yoke 2 from the upper position of the yoke 2 togetherwith the center plate 12, the lower edge portion of the cylindricalmember 19A is adhered to the second stairway surface 10 c, and thecenter plate 12 is fixed to the magnet 3 by an adhesion or the like.

Even in a speaker in which the primary coil 17A is arranged only on oneside of the secondary coil 15 like an inner magnetic typeelectromagnetic induction speaker 1A, the positioning of the primarycoil 17A to the yoke 2 can be extremely easily performed.

Although the positioning portion 8A has been provided as a stairwayportion 10A, it is also possible to form the positioning portion 8A as aconcave portion and adhere an outer peripheral surface of the lower edgeportion of the cylindrical member 19A to the periphery of the concaveportion.

In case of the foregoing inner magnetic type electromagnetic inductionspeaker 1A, although the primary coil 17A has been arranged in themagnetic gap 13 at the position between the secondary coil 15 and centerplate 12, the primary coil can be also arranged in the magnetic gap 13at a position between the secondary coil 15 and annular plate 7.

According to an inner magnetic type electromagnetic induction speaker 1Bshown in FIG. 5, a first cylindrical member to which a primary coil onthe outer peripheral side has been fixed is directly adhered to theannular plate 7.

As compared with the inner magnetic type electromagnetic inductionspeaker 1 shown in FIG. 3, the inner magnetic type electromagneticinduction speaker 1B shown below differs from the speaker 1 only withrespect to a point that a first cylindrical member is directly adheredto an annular plate. In the description of the inner magnetic typeelectromagnetic induction speaker 1B, only different portions from thoseof the inner magnetic type electromagnetic induction speaker 1 will bedescribed in detail. The other portions are designated by the samereference numerals as those shown in the similar portions in the innermagnetic type electromagnetic induction speaker 1 and their descriptionsare omitted.

The outer peripheral side primary coil 16 is wound around an innerperiphery of an upper edge portion of a first cylindrical member 18Ahaving a thin cylindrical shape and fixed. The first cylindrical member18A is formed so that its inner diameter is equal to the outer diameterof the first stairway portion 9. An inner surface of a lower edgeportion of the first cylindrical member 18A is adhered to the firststairway surface 9 a of the first stairway portion 9 of the positioningportion 8. An outer peripheral surface of the first cylindrical member18A is adhered to the inner peripheral surface of the annular plate 7.

Generally, in case of directly adhering the primary coil to the innersurface of the annular plate, since the outer peripheral surface of theprimary coil is not flat, after a flat surface is formed with anadhesive agent, it has to be adhered, so that it is very troublesome.There is a fear that when the cylindrical member is inserted into theyoke, the primary coil is come into contact with the inner surface ofthe annular plate and the primary coil is damaged.

However, like an inner magnetic type electromagnetic induction speaker1B mentioned above, by adhering the outer peripheral side primary coil16 to the annular plate 7 through the first cylindrical member 18A, theadhering operation becomes very easy and such a situation that the outerperipheral side primary coil 16 is come into contact with the annularplate 7 and damage occurs can be prevented.

According to an inner magnetic type electromagnetic induction speaker 1Cshown in FIG. 6, a positioning portion is formed as an annular groove.

As compared with the inner magnetic type electromagnetic inductionspeaker 1 shown in FIG. 3, the following inner magnetic typeelectromagnetic induction speaker 1C differs from the speaker 1 withrespect only to a point that a positioning portion is formed as anannular groove. In the description of the inner magnetic typeelectromagnetic induction speaker 1C, only different portions from thoseof the inner magnetic type electromagnetic induction speaker 1 will bedescribed in detail. The other portions are designated by the samereference numerals as those shown in the similar portions in the innermagnetic type electromagnetic induction speaker 1 and their descriptionsare omitted.

A positioning portion 8B comprises two annular grooves which areconcentrically positioned and formed on the bottom portion 5, namely, afirst groove 20 and a second groove 21 locating inside thereof.

The outer peripheral side primary coil 16 is wound around an outerperiphery of an upper edge portion of the first cylindrical member 18and fixed. The lower edge portion of the first cylindrical member 18 isfixed in the first groove 20 and the outer peripheral surface of theouter peripheral side primary coil 16 is adhered to the inner peripheralsurface of the annular plate 7.

The outer peripheral side primary coil 16 fixed to the first cylindricalmember 18 is fixed to the yoke 2, for example, by a method whereby thefirst cylindrical member 18 is inserted from the upper position into theyoke 2, the lower edge portion of the first cylindrical member 18 isfixed into the first groove 20, and the outer peripheral surface of theouter peripheral side primary coil 16 is adhered to the inner peripheralsurface of the annular plate 7.

The inner peripheral side primary coil 17 is wound around an outerperiphery of an upper edge portion of the second cylindrical member 19and fixed. A lower edge portion of the second cylindrical member 19 isfixed in the second groove 21 and an inner peripheral surface of anupper edge portion of the second cylindrical member 19 is adhered to theouter peripheral surface of the center plate 12.

The inner peripheral side primary coil 17 fixed to the secondcylindrical member 19 is fixed to the yoke 2, for example, by a methodwhereby the second cylindrical member 19 is preliminarily and externallyfitted to the center plate 12, the inner surface of the upper edgeportion of the second cylindrical member 19 is adhered to the centerplate 12, and in a state where it has been fixed to the center plate 12,the second cylindrical member 19 is inserted into the yoke 2 togetherwith the center plate 12 from the upper position of the yoke 2, and thelower edge portion is fixed into the second groove 21.

According to the foregoing positioning portion 8B, since it issufficient to form the two grooves 20 and 21 onto the bottom portion 5of the yoke 2, the positioning portion 8B can be extremely easilyformed.

As for the inner magnetic type electromagnetic induction speaker 1C,since the first cylindrical member 18 and second cylindrical member 19are fixed so as to be fitted into the first groove 20 and second groove21, respectively, the attaching strength of the outer peripheral sideprimary coil 16 and inner peripheral side primary coil 17 can be furtherimproved.

An outer magnetic type electromagnetic induction speaker 22 shown inFIG. 7 will now be described as a second embodiment.

The outer magnetic type electromagnetic induction speaker 22 comprises ayoke 23, a magnet 24, and a diaphragm 25.

The yoke 23 is constructed by integratedly forming a bottom portion 26and a center pole 27 projecting upward from a center portion of thebottom portion 26. A positioning portion 28 is integratedly formed on anupper surface of the center portion of the bottom portion 26.

The positioning portion 28 is formed as a disk-shaped stairway portion29. An outer peripheral surface 29 a of the stairway portion 29 isformed as a stairway surface. An upper surface 29 b is located slightlyupward from the upper surface of the bottom portion 26. The center pole27 is provided integratedly with a center portion of the upper surface29 b of the stairway portion 29.

The cylindrical magnet 24 is attached to an outer edge portion of theupper surface of the bottom portion 26. The magnet 24 is arranged, forexample, coaxially with the stairway portion 29 and center pole 27 bybeing arranged in a positioning concave portion (not shown) formed onthe upper surface of the bottom portion 26.

A ring-shaped annular plate 30 is attached to an upper surface of themagnet 24. The annular plate 30 is arranged in correspondence to anupper edge portion of the center pole 27. The upper edge portion of thecenter pole 27 is located in a center hole 30 a of the annular plate 30.An outer edge upper surface of the annular plate 30 is attached to aframe 31. A gap formed between the annular plate 30 and center pole 27becomes a magnetic gap 32. A magnetic circuit portion is constructed bythe yoke 23, magnet 24, annular plate 30, and center pole 27.

An inner peripheral surface of the annular plate 30 is located slightlyoutside from the stairway surface 29 a of the stairway portion 29, whilea center axis of the stairway portion 29 of the positioning portion 28is used as a reference.

The diaphragm 25 comprises: a center portion 25 a which is located inthe center portion and formed in an arc-shaped cross section; aninclined portion 25 b which is provided so as to be continuous with anouter periphery of the center portion 25 a and is deformed upward as itapproaches outward; an edge portion 25 c which is continuous with anouter periphery of the inclined portion 25 b; and a fixing portion 33which is provided so as to be continuous with an outer periphery of thecenter portion 25 a and projected in the direction opposite to that ofthe inclined portion 25 b. An outer edge portion of the edge portion 25c is attached to an upper surface of an outer edge portion of the frame31. An upper edge portion of a cylindrical bobbin 34 is fixed to an edgeportion of the fixing portion 33 by adhesion or the like.

A secondary coil 35 of one turn is wound around a portion near a loweredge of the bobbin 34 and fixed. The secondary coil 35 is located in themagnetic gap 32 formed between the annular plate 30 and center pole 27.

An outer peripheral side primary coil 36 and an inner peripheral sideprimary coil 37 are arranged in the magnetic gap 32 so as to face eachother through the secondary coil 35. The outer peripheral side primarycoil 36 is fixed to the inner peripheral surface of the annular plate30. The inner peripheral side primary coil 37 is fixed to the upper edgeportion of the outer peripheral surface of the center pole 27. The outerperipheral side primary coil 36 and inner peripheral side primary coil37 are serially connected. One end of the outer peripheral side primarycoil 36 and one end of the inner peripheral side primary coil 37 areconnected to signal lead wires 36 a and 37 a to which an audio signalfrom an audio signal reproducing unit (not shown) is supplied,respectively.

The outer peripheral side primary coil 36 is wound around an outerperiphery of an upper edge portion of a first cylindrical member 38formed so as to have a thin cylindrical shape and fixed. The firstcylindrical member 38 is formed so that its inner diameter is equal tothe outer diameter of the stairway portion 29 of the positioning portion28. An inner surface of a lower edge portion of the first cylindricalmember 38 is adhered to the stairway surface 29 a of the stairwayportion 29. An outer peripheral surface of the outer peripheral sideprimary coil 36 fixed to the first cylindrical member 38 is adhered tothe inner peripheral surface of the annular plate 30.

The outer peripheral side primary coil 36 fixed to the first cylindricalmember 38 is fixed to the yoke 23, for example, by a method whereby theouter peripheral side primary coil 36 fixed to the first cylindricalmember 38 is preliminarily adhered to the inner peripheral surface ofthe annular plate 30, and in a state where it has been fixed to theannular plate 30, the cylindrical member 38 is inserted into a centerhole 24 a of the magnet 24 from the upper position of the magnet 24together with the annular plate 30, and a lower edge portion of thefirst cylindrical member 38 is adhered to the stairway surface 29 a ofthe stairway portion 29 of the positioning portion 28. By externallyfitting the first cylindrical member 38 to the stairway portion 29, thepositioning of the outer peripheral side primary coil 36 to the yoke 2is performed. Thus, the positioning of the annular plate 30 to themagnet 24 attached to the yoke 2 is also simultaneously performed. Theannular plate 30 is fixed to the magnet 24 by using proper means such asadhesion, screwing, or the like.

The inner peripheral side primary coil 37 is wound around an outerperipheral of an upper edge portion of a second cylindrical member 39having a thin cylindrical shape and fixed. The second cylindrical member39 is formed so that its inner diameter is almost equal to the outerdiameter of the center pole 27. The second cylindrical member 39 isadhered in a state where its inner surface is externally fitted to thecenter pole 27.

The inner peripheral side primary coil 37 fixed to the secondcylindrical member 39 is fixed to the center pole 27 by, for example,externally fitting the second cylindrical member 39 to the center pole26 and adhering it.

As mentioned above, in the outer magnetic type electromagnetic inductionspeaker 22, the positioning portion 28 is formed on the yoke 2 and thefirst cylindrical member 38 to which the outer peripheral side primarycoil 36 is fixed and the second cylindrical member 39 to which the innerperipheral side primary coil 37 is fixed are merely externally fitted tothe stairway portion 29 of the positioning portion 28 and the centerpole 27 formed integratedly with the yoke 2, so that the positioning ofthe outer peripheral side primary coil 36 and inner peripheral sideprimary coil 37 to the yoke 2 can be performed.

Therefore, the positioning of the outer peripheral side primary coil 36and inner peripheral side primary coil 37 to the yoke 2 can be extremelyeasily performed and there is no need to use the foregoing gap gaugewhich has conventionally been used, so that there is no fear of dropoutfrom the yoke 2 or the like due to the contact of the gap gauge with theouter peripheral side primary coil 36 or inner peripheral side primarycoil 37.

The first cylindrical member 38 is adhered to the stairway surface 29 aof the positioning portion 28, the outer peripheral side primary coil 36fixed to first cylindrical member 38 is adhered to the annular plate 30,and the second cylindrical member 39 is adhered to the center pole 27,so that an adhering area increases and an adhering strength of the outerperipheral side primary coil 36 and inner peripheral side primary coil37 is improved.

As for the positioning portion 28, it is sufficient to merely form thestairway portion 29 on the bottom portion 26 of the yoke 2, so that thepositioning portion 28 can be easily formed.

Although the foregoing positioning portion 28 is formed as a stairwayportion 29 which is projected upward, the positioning portion can bealso formed as a concave portion which opens upward, so that the firstcylindrical member 38 is adhered to the peripheral surface of theconcave portion. The positioning portion can be formed as an annulargroove and the lower edge portion of the first cylindrical member 38 canbe inserted and fixed into the groove.

Although the construction in which the outer peripheral side primarycoil 36 and inner peripheral side primary coil 37 which face each otherthrough the secondary coil 35 are arranged in the outer magnetic typeelectromagnetic induction speaker 22 has been shown, it is also possibleto construct an outer magnetic type electromagnetic induction speaker inwhich a primary coil is arranged only on one of the outer peripheralside and the inner peripheral side of a secondary coil.

Although the outer magnetic type electromagnetic induction speaker 22 inwhich the outer peripheral side primary coil 36 is directly adhered tothe annular plate 30 has been shown, the outer peripheral side primarycoil can be fixed to the inner peripheral surface of the firstcylindrical member and the upper edge portion of the inner peripheralsurface of the first cylindrical member can be directly adhered to theannular plate 30.

The specific shape and structure of each portion shown in each of theabove embodiments are shown as mere specific examples when the inventionis embodied. The technical scope of the invention should not belimitedly interpreted by them.

As will be obvious from the above description, the speaker apparatus ofthe invention comprises: the bobbin fixed to the diaphragm; the yokewhich forms the magnetic circuit together with the magnet and in whichthe positioning portion is formed; the primary coil which is arranged inthe magnetic gap and to which the audio signal is inputted; and thesecondary coil which is provided for the bobbin and arranged in themagnetic gap, wherein the apparatus has the cylindrical member in whichthe primary coil is fixed to one end portion and the other end portionis attached to the positioning portion of the yoke.

Therefore, since the positioning of the primary coil to the yoke can beextremely easily performed and there is no need to use the gap gauge,there is no fear of dropout from the yoke or the like due to the contactof the gap gauge with the primary coil.

The attaching area increases due to the direct attachment of the primarycoil or the attachment thereof through the cylindrical member and theattaching strength can be improved.

According to the invention of Claim 2, the speaker apparatus comprisesthe annular plate having the center hole and the center member arrangedinside of the annular plate, wherein the magnetic gap is formed betweenthe annular plate and the center member and the primary coil is arrangedbetween the annular plate and the secondary coil or between the centermember and the secondary coil.

Even in case of the speaker apparatus in which the primary coil isarranged only on one side of the secondary coil, the positioning of theprimary coil to the yoke can be extremely easily performed.

According to the invention of Claim 3, the speaker apparatus comprisesthe annular plate having the center hole and the center member arrangedinside of the annular plate, wherein the magnetic gap is formed betweenthe annular plate and the center member and the primary coil is fixed tothe inner peripheral surface of the annular plate through thecylindrical member or fixed to the outer peripheral surface of thecenter member through the cylindrical member, so that the fixingoperation becomes very easy and such a situation that the primary coilis come into contact with the annular plate or center member and damageoccurs does not occur.

According to the invention of Claim 4, the speaker apparatus comprisesthe annular plate having the center hole and the center member arrangedinside of the annular plate, wherein the magnetic gap is formed betweenthe annular plate and the center member and the primary coil is arrangedbetween the annular plate and the secondary coil and between the centermember and the secondary coil, respectively.

Even in case of the speaker apparatus in which the primary coils arearranged so as to sandwich the secondary coil, the positioning of theprimary coil to the yoke can be extremely easily performed.

According to the invention of Claim 5, since the positioning portionprovided for the yoke is formed as a stairway portion, the positioningportion can be easily formed.

According to the invention of Claim 6, since the positioning portionprovided for the yoke is formed as an annular groove, the positioningportion can be extremely easily formed.

Since the cylindrical member can be fixed by fitting it into the groove,the attaching strength of the primary coil can be further improved.

The construction in which the bobbin is adhered to the diaphragm hasbeen described as an example in the foregoing embodiment. A detailedconstruction of the coupling portion of the diaphragm and the bobbinwill now be described with reference to the following drawings. As aspeaker which will be explained by using the following drawings, aninner magnetic type electromagnetic induction speaker will be describedas an example. Although the inner magnetic type electromagneticinduction speaker will be described as an example with respect to thecase where the secondary coil itself constructs a bobbin, the inventioncan be also applied to an inner magnetic type speaker of a type in whichthe secondary coil is attached to the bobbin shown in FIGS. 3 to 6.

A speaker apparatus 319 shown in FIGS. 8 and 9 in which a bobbin and aconductive ring serving as a secondary coil are directly fixed will bedescribed.

The speaker apparatus 319 comprises a yoke 320, a magnet 321, and adiaphragm 322.

The yoke 320 is constructed by integratedly forming a disk-shaped bottomportion 323, a peripheral wall portion 324 projected upward from aperipheral edge of the bottom portion 323, and a ring-shaped annularplate 325 provided at an upper edge of the peripheral wall portion 324.The cylindrical magnet 321 is attached to a center portion of an uppersurface of the bottom portion 323. As for the yoke 320, an upper surfaceof the annular plate 325 is attached to a frame 326.

A disk-shaped center plate 327 is attached to an upper surface of themagnet 321. The center plate 327 is arranged in a center hole 325 a ofthe annular plate 325. A gap formed between the annular plate 325 andcenter plate 327 is a magnetic gap 328.

The diaphragm 322 is molded so that the whole portion is formed in analmost dome shape by press working a metal material, for example, asheet-shaped material such as aluminum, titanium, or the like or asheet-shaped material made of a high molecular material, or the like.The diaphragm 322 is constructed by integratedly forming: an almostsemispherical dome portion 329 locating in a center portion; a couplingportion 330 which is continuous with an outer periphery of the domeportion 329; an edge portion 331 which is continuous with an outerperiphery of the coupling portion 330 and has a small almost arc-shapedcross section; and a portion 332 which is to be attached and iscontinuous with an outer periphery of the edge portion 331. The portion332 to be attached is attached to an upper surface of the frame 326.

The coupling portion 330 comprises: an inner peripheral portion 330 awhich is located on the dome portion 329 side and is extended in thevertical direction; and a flat surface portion 330 b which is continuouswith a lower edge of the inner peripheral portion 330 a and faces in thevertical direction. As for the diaphragm 322, the flat surface portion330 b of the coupling portion 330 for coupling the dome portion 329 andedge portion 331 is particularly thinly formed because it is stretchedin both directions at the time of a pressing work. An upper edge portionof a cylindrical conductive ring 333 is fixed to a lower surface of theflat surface portion 330 b by, for example, an adhesive agent 334 of anepoxy resin system.

The bobbin and the conductive ring 333 serving as a secondary coil areformed fairly thickly than the bobbin 14 in the speaker apparatus 1mentioned above in order to reduce their electrical resistances. Theconductive ring 333 is formed so that its thickness is equal to a widthof flat surface portion 330 b of the diaphragm 322.

The adhesive agent 334 is coated onto the whole lower surface of theflat surface portion 330 b. An upper edge surface of the conductive ring333 is adhered to the flat surface portion 330 b through the adhesiveagent 334. An almost lower half portion of the conductive ring 333 islocated in the magnetic gap 328 formed between the annular plate 325 andcenter plate 327.

An outer peripheral side coil 335 and an inner peripheral side coil 336are arranged in the magnetic gap 328 so as to face each other throughthe conductive ring 333. The outer peripheral side coil 335 is adheredto an inner peripheral surface of the annular plate 325. The innerperipheral side coil 336 is adhered to an outer peripheral surface ofthe center plate 327. The outer peripheral side coil 335 and innerperipheral side coil 336 are serially connected. One end of the outerperipheral side coil 335 and one end of the inner peripheral side coil336 are connected to signal lead wires (not shown) to which an audiosignal from an audio signal reproducing unit (not shown) is supplied,respectively.

When a current based on the audio signal from the audio signalreproducing unit (not shown) is supplied to the outer peripheral sidecoil 335 and inner peripheral side coil 336 through the signal leadwires (not shown), an induction current flows in the conductive ring 333arranged in the magnetic gap 328 and the diaphragm 322 vibrates. Auaudible sound based on the audio signal supplied from the audio signalreproducing unit is generated.

In the foregoing speaker apparatus 319, since the adhesive agent 334 hasbeen coated to the flat surface portion 330 b formed particularlythinly, the substantial thickness of the flat surface portion 330 bincreases and the mechanical strength of the flat surface portion 330 bis enhanced.

Therefore, since vibrations whose phases are deviated by 180° do notoccur at a specific frequency in the dome portion 329 and edge portion331, while the flat surface portion 330 b is used as a node, a dip of asound pressure is not caused. Thus, since good frequency characteristicsare obtained, a quality of an audio signal to be generated can beimproved.

As mentioned above, since the adhesive agent 334 has been coated on thewhole lower surface of the flat surface portion 330 b, the mechanicalstrength of the flat surface portion 330 b is very large and a qualityof the audio signal to be generated can be further improved.

By forming in such a manner that the width of flat surface portion 330 bis equal to the thickness of conductive ring 333 adhered to the flatsurface portion 330 b as mentioned above, the mechanical strength of theflat surface portion 330 b is very large.

The invention is not limited to the construction shown in FIG. 9 but canbe applied to a speaker apparatus as shown in, for example, FIG. 10 or11. Although a construction of only a coupling portion of a diaphragmand a bobbin is shown in each of FIGS. 10 and 11, a construction of theother portions of the speaker apparatus is similar to that of thespeaker apparatus shown in FIG. 9. Portions common to those in FIG. 9are designated by the same reference numerals and their detaileddescriptions are omitted.

In the speaker apparatus shown in FIG. 10, a secondary coil 317 of oneturn made of a conductive material is wound around or fixed to a bobbin315 made of an insulative material. The bobbin 315 is cylindricallyformed, one end side is adhered to the lower surface 330 b of the flatsurface portion 330, and the other end side is inserted into themagnetic gap 328 so that the secondary coil 317 faces the primary coils335 and 336. An adhesive agent 316 is coated onto the lower surface 330b of the flat surface portion 330 of the diaphragm 322 so that its crosssectional shape becomes a handstand triangular shape, thereby allowingthe bobbin 315 to be fixed to the flat surface portion 330 of thediaphragm 322.

In the speaker apparatus shown in FIG. 11, the secondary coil 317 iswound around or fixed to a bobbin 315A in a manner similar to thespeaker apparatus shown in FIG. 10 mentioned above. The bobbin 315A iscylindrically formed by using aluminum, titanium, or the like and has abending portion 318 whose one end side is bent to the outside at a rightangle. The adhesive agent 316 is coated to one surface of the bendingportion 318 or the lower surface 330 b of the flat surface portion 330.One end side of the bobbin 315A, namely, the bending portion 318 isfixed to the flat surface portion 330 b of the diaphragm 322.

The invention is not limited to each of the foregoing embodiments butmany various modifications and variations are possible within the scopeof the invention without largely departing from the spirit of theinvention.

What is claimed is:
 1. A speaker apparatus comprising: a magneticcircuit portion having a magnet, a yoke on which said magnet isprovided, and a top plate for forming a magnetic gap together with saidyoke; at least one primary coil arranged in the magnetic gap of saidmagnetic circuit portion; a diaphragm; a secondary coil provided forsaid diaphragm so as to face said primary coil in said magnetic gap; acylindrical member in which one side located in said magnetic gap isattached to said primary coil; and a positioning portion, provided insaid yoke, for positioning the other side of said cylindrical member,wherein said positioning portion is a stairway portion provided in saidyoke.
 2. An apparatus according to claim 1, wherein said one side ofsaid cylindrical member is arranged between said primary coil and saidmagnetic circuit portion.
 3. An apparatus according to claim 1, whereinsaid diaphragm comprises: a diaphragm portion formed almost in a domeshape; an edge portion provided on an outer peripheral side of saiddiaphragm portion; and a flat portion provided between said diaphragmportion and said edge portion, and said secondary coil is arranged onsaid flat portion.
 4. An apparatus according to claim 3, wherein one endside of said secondary coil is attached to said flat portion.
 5. Anapparatus according to claim 3, further comprising a bobbin for whichsaid secondary coil is provided and whose one end is attached to saidflat portion of said diaphragm.
 6. An apparatus according to claim 5,wherein a bending portion is formed on one end side of said bobbin andsaid bending portion is adhered to said flat portion of said diaphragm.7. A speaker apparatus comprising: a magnetic circuit portion having amagnet, a yoke on which said magnet is provided, and a top plate forforming a magnetic gap together with said yoke; a first primary coilarranged in the magnetic gap of said magnetic circuit portion; adiaphragm; a secondary coil provided for said diaphragm so as to facesaid primary coil in said magnetic gap; a first cylindrical member inwhich one side located in said magnetic gap is attached to said firstprimary coil; a positioning portion, provided for said yoke, forpositioning the other side of said cylindrical member; a second primarycoil which is arranged in said magnetic gap of said magnetic circuitportion so as to face said first primary coil through said secondarycoil; and a second cylindrical member in which said second primary coilis attached to one side located in said magnetic gap, wherein the otherside of said second cylindrical member is positioned by said positioningportion, and said first primary coil and said second primary coil areserially connected.
 8. An apparatus according to claim 7, wherein saidpositioning portion is constructed by: a first stairway portion forpositioning the other side of said cylindrical member formed on saidyoke; and a second stairway portion for positioning the other side ofsaid another cylindrical member.
 9. An apparatus according to claim 8,wherein said first positioning portion and said second positioningportion are formed in a bottom portion of said yoke so as to have astairway shape.
 10. An apparatus according to claim 7, wherein saidpositioning portion is constructed by: a first groove portion forpositioning the other side of said cylindrical member formed on saidyoke; and a second groove portion for positioning the other side of saidanother cylindrical member.
 11. An apparatus according to claim 7,wherein said another primary coil is provided at a position where itfaces said primary coil of said yoke, and said another cylindricalmember is arranged so as to face said secondary coil in said magneticgap.
 12. An apparatus according to claim 7, wherein said one side ofsaid another cylindrical member is arranged between said another primarycoil and said magnetic circuit portion.